on the preparation of epdm-g-mah compatibilizer via melt

Journal of Mechanical Engineering and Sciences

ISSN (Print): 2289-4659; e-ISSN: 2231-8380

Volume 13, Issue 3, pp. 5424-5440, September 2019

© Universiti Malaysia Pahang, Malaysia

DOI: https://doi.org/10.15282/jmes.13.3.2019.14.0440

5424

On the preparation of EPDM-g-MAH compatibilizer via melt-blending method

J. A. Razak1, N. Mohamad1, M. A. Mahamood1, R. Jaafar1, I. S. Othman1,

M. M. Ismail2, L. K. Tee3, R. Junid4 and Z. Mustafa1

1Fakulti Kejuruteraan Pembuatan, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya,

76100, Durian Tunggal, Melaka, Malaysia, *Email: [email protected]

Phone: +60126087651; Fax: +6062701047 2Fakulti Kejuruteraan Elektronik & Kejuruteraan Komputer, Universiti Teknikal Malaysia

Melaka, Hang Tuah Jaya, 76100, Durian Tunggal, Melaka, Malaysia, 3Fakulti Teknologi Kejuruteraan Mekanikal & Pembuatan, Universiti Teknikal Malaysia

Melaka, Hang Tuah Jaya, 76100, Durian Tunggal, Melaka, Malaysia, 4Faculty of Mechanical Engineering, Universiti Malaysia Pahang,

26600, Pekan, Pahang, Malaysia

ABSTRACT

This paper presents an experimental investigation to determine the optimum composition of

maleic anhydride (MAH) and dicumyl peroxide (DCP) as initiator, for ethylene-propylene-

diene-monomer grafted MAH (EPDM-g-MAH) compatibilizer preparation, using Response

Surface Methodology (RSM) approach. EPDM-g-MAH was prepared in the laboratory scale

by melt blending method using an internal mixer. For this study, the effects of MAH (2.50 –

7.50 wt.%) and DCP (0.10 – 0.30 wt.%) towards grafting efficiency was determined. Two

level full factorial design of experiment (DOE) has applied to establish the relationship

between these two independent factors of raw materials. Analysis of variance (ANOVA) and

the optimization menu have utilized to decide the raw materials formulation with maximum

grafting efficiency. Quantitative analysis based on infrared (IR) spectral intensity supported

by 1H-NMR spectral are used to propose for EPDM-g-MAH grafting mechanism. Standard

calibration curve for quantity ratio plot was exponential with R2 = 89.19%. It has found that

an optimum about 8.52% of MAF grafting efficiency has yielded about DCP factor

contributed larger effect at 67.45% of contribution effect. Anhydride stretching of grafted

C=O as confirmed by FTIR peak at 1713 cm-1 and 1770 – 1792 cm-1 has responsible for

MAH grafting into EPDM rubber. Based on FTIR, 1H-NMR and 2D-COSY spectral analysis,

reaction mechanism for EPDM-g-MAH grafting has successfully proposed with two possible

termination steps. In overall, this study was significant to introduce the simplest optimum

method of laboratory scale EPDM-g-MAH compatibilizer using melt blending and DOE

approach.

Keywords: EPDM-g-MAH grafting; RSM; DOE; standard calibration; IR quantitative

analysis.

https://doi.org/10.15282/jmes.13.3.2019.14.04

J. A. Razak et. al / Journal of Mechanical Engineering and Sciences 13(3) 2019 5424-5440

5425

INTRODUCTION

EPDM is a specialty elastomer for engineering and technology application. This synthetic

rubber has synthesized from the polymerization of ethylene and propylene with small amount

of non-conjugated diene at about 3 – 9% [1]. EPDM is non-saturated and non-polar due to

lower content of –C=C- [2]. The chemical structure of EPDM has illustrated as in the

following Figure 1. EPDM not possessed the polar group or any chemical group with higher

electron density. This situation complicates the bond between EPDM and other materials.

EPDM with higher unsaturation level is more compatible with diene rubber such as natural

rubber (NR) to improve their waste, heat, ozone, weather, environment and impact resistance

[3].

Figure 1. Chemical structure of EPDM rubber [4].

Normally, in the preparation of NR/EPDM blend, the EPDM phase component is relatively

critical to consider because of its advantages as impact modifier, resistance enhancer towards

heat and chemical and superior ageing properties [5]. However, non-polarity and highly

unsaturation behaviour of EPDM are the main cause incompatibility and immiscibility of

elastomer blends that involve the presence of EPDM rubber phase. EPDM rubber

modification need to perform through copolymer product preparation using simple grafting

method to enhance the blend compatibility [6]. The copolymer products obtained used as a

compatibilizer for most of rubber blends [7]. This study was to prepare the copolymer of

EPDM grafted with MAH (EPDM-g-MAH) by melt blending using a design of experiment

approach.

Grafting of EPDM with MAH produces elastomer with local polarity and increasing

chemical reactivity [8]. The use of EPDM-g-MAH compatibilizer has dual-function acting

on an anhydride-polar part, which results in a good affinity to the filler surface, while the

polymer that attached gives the compatibilization effects and interaction to the blends [9].

EPDM modifications with MAH, are expected to increase the cross-link density if EPDM

phase resulting in higher polarity for uniformity of curative distribution [10].

A recent study involving the preparation of EPDM-g-MAH was reported [6, 11-13,

18]. Grigoryeva and Karger-Kocsis (2000) have successfully evaluated the impact of MAH

grafted to EPDM by taking into account various preparation factor of compatibilizer such as

MAH content, grafting temperature, rotor speed and mixing chamber volume [12]. The same

applies to the compatibilizer preparation for poly (butylene succinate) grafted with MAH

(PBS-g-MAH) by Phua et al. (2013) [9]. The study suggests that the DCP initiator content is

around 1.00 – 1.50 phr without involving the any interaction factor between the studied

independent and dependent variables.

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwicxfus44DKAhWOUI4KHTi-CoIQjRwIBw&url=http://www.google.com/patents/US7713539&bvm=bv.110151844,d.c2E&psig=AFQjCNHAljmVe-BfUoAosvV9n-_qupoRYA&ust=1451468409376776


5426

Hence, this study took the opportunity to manipulate the DOE approach in analysing

the grafting efficiency as response studied and establishing the relationship between the

independent and dependent variables [19-24]. In addition, this study also reporting on the

utilization of quantitative IR based on FTIR spectral analysis for grafting efficiency

determination. At the end, the suggested reaction mechanism was further supported by the 1H-NMR and 2D-COSY analysis.

METHODS AND MATERIALS

Raw Materials

EPDM rubber grade BUNA EP 9650 has supplied by LANXESS, Pittsburgh, USA. Mooney

viscosity UML (1+8) at 150°C is around 60±6 MU, with ethylene content of about 54±4

wt.%, ENB content of 6.5±1.1 wt.% with volatile content of ≤ 0.75 wt.%, specific gravity at

0.86 and ash content of ≤ 0.50 wt.%. MAH used was a synthesis grade (95% with maleic

acid content ≤ 5.00 %), supplied by Sigma Aldrich Chemie GmbH, Steinheim, Germany.

The dicumyl peroxide used is bis (1-methyl-1-phenyl-ethyl) peroxide bis (α-α – dimethyl

benzyl peroxide) with molecular weight formula of 270.37, volatile density around 9.30 and

steam pressure at 15.40 mmHg. DCP was supplied by Sigma Aldrich, Germany with addition

content in the range of 0.10 – 0.50 wt.%.

EPDM-g-MAH Compatibilizer Preparation

The EPDM-g-MAH compatibilizer has prepared by melt-blending using an internal mixer

model Haake Polylab OS Rheodrive 16 with Banbury rotor and fill factor of 0.70. The effects

of added DCP and MAH was screened as independent variables for EPDM-g-MAH

compatibilizer melt blending by using a two-level full factorial design of experiment. The

grafting efficiency as response chosen as dependent variable. The two-level full factorial

experiments based on two numerical factor, no categorical factor, involving only one

replication with three midpoints and no blocking. Overall, the software has proposed about

seven experiment on the preparation of EPDM-g-MAH compatibilizer. The following Table

1 summarized the experimental design used in this study. Table 2 outlined the lower, mid

and upper level value of each variable. From the experimental results, the effects of

independent variables towards grafting efficiency determined by half-normal plot and the

effects list. The factorial model chosen and analysed using the analysis of variance (ANOVA)

to test the selected model accuracy. Pure EPDM sample also characterized as a control

sample.

Table 1. The selected level for variables.

MAH content (A, wt.%) DCP content (B,

wt.%)

2.50 (-1) 0.10 (-1)

5.00 (0) 0.30 (0)

7.50 (+1) 0.50 (+1)


5427

The grafting process was performed at basic formulation recipe of 100% EPDM (43 grams)

with ρEPDM = 0.802 g/cm3. At first, the EPDM masticated at 30°C within 10 minutes using

the open two-roll mill equipment. Next, the grafting of EPDM-g-MAH performed in an

internal mixer at fixed processing parameters as suggested by Grigoryeva & Karger-Kocsis,

(2000), which are 180°C of blending temperature, 75 rpm of Banbury rotor speed and within

5 minutes of grafting period [12]. Later the grafted EPDM samples were conditioned at 25°C

within 24 hours before thin films preparation of EPDM-g-MAH samples for Fourier

transform infra-red (FTIR) analysis.

Table 2. Overall experimental plan and formulation recipes for grafting of

EPDM-g-MAH compatibilizer preparation

Standard

Test

Block

Factor 1 Factor 2

Sample

Code

Weight

EPDM

Weight

MAH

Weight

DCP A:MAH B:DCP

wt.% wt.% (grams) (grams) (gram)

6 1 1 5.00

(0)

0.30

(0) EM1 43.00 2.150 0.129

4 2 1 7.50

(+1)

0.50

(+1) EM2 43.00 3.225 0.215

2 3 1 7.50

(+1)

0.10

(-1) EM3 43.00 3.225 0.043

5 4 1 5.00

(0)

0.30

(+1) EM4 43.00 2.150 0.129

1 5 1 2.50

(-1)

0.10

(-1) EM5 43.00 1.075 0.043

3 6 1 2.50

(-1)

0.50

(0) EM6 43.00 1.075 0.215

7 7 1 5.00

(0)

0.30

(0) EM7 43.00 2.150 0.129

FTIR Characterization

For thin film preparation, the EPDM-g-MAH samples were hot-pressed at 150°C, within 10

minutes using compressive pressure at 5MPa. Prior to that, five minutes of pre-heat allocated

before performing the hot press. The thin films conditioned by immersing it into acetone

solution for 30 minutes and drying at 75°C for 24 hours, before the FTIR test has performed.

This purification step is important to remove the non-reacted MAH and increase the

absorption peak in the same area of the anhydride [14, 15]. The elimination of unreacted

MAH has confirmed from the missing of absorption peak at 700 cm-1 due to single and double

C bonds to MAH [6]. The FTIR spectra is recorded using the Jasco Pro 450 FT/IR-6100(a)

equipment, from 2000 to 400 cm-1 wavenumber with a type II laser resolution. A total of 50

times the number of scans on the sample held at vertical position has performed. Later, the

obtained IR spectral was then smoothen prior of the quantitative analysis.


5428

NMR Characterization

The nuclear magnetic resonance (NMR) analysis of 1H-NMR and 2D-COSY utilized to

confirm the success of MAH grafting into EPDM rubber. It also used as a tool for proposal

of EPDM-g-MAH reaction mechanism. The NMR test performed by using the spectrometer

Bruker Avance 300 MHz with pulse rate of 13.2 μs with transition period of 3.0 seconds. The

EPDM-g-MAH film completely immersed in deuterated chloroform (CDCl3) solution and

tetramethylsilane (TMS) solution used as standard for internal chemical shift. The two-

dimensional correlation spectroscopy (2D-COSY) also recorded with delayed time of 1.62

seconds and scan width of 1930.5 Hz. 1H-NMR and 2D-COSY are able to provide extra

information on grafting mechanism based on the presence of protons in the tested grafted

polymers [9].

RESULTS AND DISCUSSION

The comparison of FTIIR spectra between pure EPDM rubber, MAH and grafted EPDM-g-

MAH depicts in the Figure 2. For pure EPDM rubber, the peaks at 2926 and 2856 cm-1 were

typical of EPDM indicating the presence of saturated hydrocarbon backbone of aliphatic

alkyl symmetric or asymmetric C-H stretching vibration. IR spectra for EPDM-g-MAH is

referred [15, 25, 26]. The absorption bands at the region of 1770 – 1792 cm-1, which attributed

to C=O symmetric stretching bonds, were related to successful MAH grafted to the EPDM

rubber [27, 28, 29]. The absorption peak at 922 cm-1, confirmed the presence of OH group in

EPDM-g-MAH. The missing absorption peak at 1779 to 1780 cm-1 that indicate C-O

stretching for anhydrides of pure EPDM has confirmed the success of EPDM grafting with

MAH [30]. This condition also applies to all IR spectral for grafted EPDM-g-MAH as

depicted in the Figure 3.

Wavenumber (cm-1

)

1000 2000 3000 4000

Tra

nsm

itta

nce

(a

.u)

Pure EPDM

MAH

EPDM-g-MAH

711 cm-1

1376 cm-1

1466 cm-1

2856 - 2926 cm-1

922 cm-1

1713 cm-1

1770 - 1792 cm-1

Figure 2. IR spectral comparison between pure EPDM (control sample), MAH and grafted

EPDM-g-MAH [15].


5429

For quantitative analysis of IR spectral for EPDM-g-MAH grafting process, the following

Figure 3 shows the selected spectral for comparison. For this purpose, spectral from EM1,

EM2 and EM5 have selected. The quantitative analysis of IR spectral performed based on

DOE and the application of Beer-Lambert equation for grafting efficiency determination for

EPDM-g-MAH grafting process. Analysis for the entire peaks has made for detecting the

anhidrida and selection of internal standard. It was found that there are two important area

for anhydride zone, which are peak range at 1860 – 1738 cm-1 and 1156 – 1098 cm-1. For IR

spectral, the peak intensity was directly proportional with quantity (A); absorbance. The

calculation of quantity ratio from IR spectral for determination of grafted MAH was based

on absorbance rule that also been known as Beer’s Law, which can be summarized in the

following Equation 1:

A = -log T = log 𝐼𝑜

𝐼 = ɛ𝑙𝑐 (1)

Where, ε is a molar absorbance, l is a sample thickness and c is a concentration value. Both

ε and l can be obtained from the calibration curve of A versus c for all the prepared

samples with known concentration value. For material analysis with presence of two

components, ration method is used for quantitative analysis based on Beer’s Law.

Referring to Equation (1), in the spectrum depicted in Figure 3, there are two-component

presence whereby both component having its distinctive peak and not interfering between

each other. Hence, it was assumed that the ration of quantities is not dependent on the

thickness of the film, so the quantity ratio can be calculated by using the following

Equation (2).

𝐴1

𝐴2=

ɛ1𝐶1𝑙1

ɛ2𝐶2𝑙2=

ɛ1𝐶1

ɛ2𝐶2 (2)

For material system with the presence of two components, the blend ratio was simplified as

the Equation (3).

X1 + X2 = 1 (3)

Hence, the quantity ratio is determined as the following Equation (4).

𝐴1

𝐴2=

ɛ1𝑥1

ɛ2𝑥2=

ɛ1

ɛ2(

1

𝑋2− 1) = −𝑘 + 𝑘

1

𝑥2 (4)

where, k is the molar absorbance and is given in the following Equation (5).

𝑘 =ɛ1

ɛ2 (5)


5430

(a)

(b)

(c)

Figure 3. Selected IR spectral for grafted EPDM-g-MAH: (a) EM1, (b) EM2, (c) EM5.

EM 1

MAH: 5.00 wt. %; DCP: 0.30 wt. %

EM 2

MAH: 7.50 wt. %; DCP: 0.50 wt. %

EM: 5

MAH: 2.50 wt. %; DCP: 0.10 wt. %


5431

In this study, peak at wavenumber 1466.60 cm-1 was selected as an internal standard after

considering the consistent peak intensities at that particular wavenumber [16]. This peak is

referred to the scissoring frequency for methylene, CH2 in EPDM component. For quantity

ratio calculation, the peak that represent C=O anhydride stretching at 1738.50 cm-1 is utilized.

Standard calibration curve is plotted based on various MAH content (0, 2.50, 5.00 and 7.50

wt. %) and as presented as in the following Figure 4. The quantity ratio plots has

exponentially increased with the MAH content. The calibration curve with MAH content

function gives one exponent equation as in Equation 6 with R2 value around 0.8919.

𝑦 = 0.0122𝑒0.37266𝑥 (6)

% 𝑀𝐴𝐻 𝑔𝑟𝑎𝑓𝑡𝑒𝑑 𝑖𝑛𝑡𝑜 𝐸𝑃𝐷𝑀 =1

0.3726(ln [

𝐴1738.51𝑐𝑚−1

𝐴1466.60𝑐𝑚−1

0.0122]) (7)

The quantity of grafted MAH was then determined by using modified Equation 7 from the

original Equation 6, considering the quantity ration for IR peak wavenumber range at 1738.50

and 1466.60 cm-1. The percentage of grafted MAH was calculated and reported in the Table

3. Later, the normal half plot has generated by using the DOE software and depicted in the

following Figure 5. From the half-normal plot, it was found that the variables A and B and

interaction term of AB were deviated away from the straight plot line. No variables and

interacting points are detected falls over the plot line. Based on this plot, both variables A

(MAH content) and B (DCP content) are significant models.

Figure 4. Standard calibration curve for EPDM-g-MAH for quantity ratio determination.

This decision has supported by a list of effects that indicate the numerical representation of

each model terms, as in the Table 4. Variable B (DCP content) is the most significant factor

with percentage of contribution about 67.45%. Interaction term of AB followed with 20.87%

of contribution in the effect list. Both B and AB are positive value indicating that addition of

A and B from low level into higher level, prone to increase the grafting efficiency of MAH.

y = 0.0122e0.3726x

R² = 0.8919

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0 2.5 5 7.5

Qu

an

tity

Rati

o (

arb

. u

nit

)

wt.% of MAH content addition

Abs 1738.51/Abs 1466.60


5432

DCP increased the radical formation during the grafting reaction that assisting the molecular

chain movement into the rubber backbone [9]. ANOVA for quantity ratio determination as

summarized in Table 5. Both variable of A and B are significant model terms with p-value

less than 0.0500. The selected model has considered accurate and used to navigate the design

analysis area with higher coefficient of determination, R2. The selected model does not

explain only 0.03% of total variation.

Table 3. Percentage of grafted MAH into EPDM calculated using absorbance ratio analysis.

Sample

Factor 1 Factor 2 Internal

Standard

Standard

anhydride peak

A: MAH B: DCP 1466.60 cm-

1

1738.51 cm-

1 Response

wt.% wt.% arb. unit arb. unit % grafting

efficiency

Control 0 0 96.40 1.38 0.00

EM1 5.0 0.3 98.89 4.28 3.40

EM2 7.5 0.5 96.34 28.00 8.52

EM3 7.5 0.1 96.16 2.08 1.54

EM4 5.0 0.3 97.05 4.06 3.31

EM5 2.5 0.1 99.54 3.25 2.64

EM6 2.5 0.5 98.59 6.74 4.63

EM7 5.0 0.3 99.88 4.42 3.46

Table 4. Effect lists of each model term involved in EPDM-g-MAH grafting process.

Term Studentised Effects Total Square % Contribution

A 1.39 1.95 6.53

B 4.48 20.12 67.45

AB 2.50 6.23 20.87


5433

Figure 5. Half-normal plot of quantity ratio analysis for EPDM-g-MAH grafting efficiency

studies.

Table 5. Analysis of variance for testing data utilizing the quantity ratio calculation.

Variation Total of square Degree of freedom Average of square Fo P-value

Model 28.29 3 9.43 1654.17 0.0006

A 1.95 1 1.95 341.41 0.0029

B 20.12 1 20.12 3528.99 0.0003

AB 6.23 1 6.23 1092.11 0.0009

Curvature 1.52 1 1.52 267.16 0.0037

Error 0.011 2 5.6700e-003

Total 18075.52 6

Regression model for MAH grafting experiment is given in the following Equation 8. For

this equation, variables A and B represented the MAH and DCP content, respectively. The

note (+) at each level indicates both MAH and DCP are at the highest increment level. The

regression coefficient +0.70 and +2.24 are one-half for the expected impact factor based on

two-unit changes (from -1 to +1).

Quantity Ratio = + 4.33 + 0.70*A + 2.24*B + 1.25*A*B (8)

Figure 8 presents a three dimensional plot for grafting efficiency response surface based on

the selected model, with MAH and DCP content as the regresses coefficient. Based on the

corresponding surface evaluation, it is clear that the grafting efficiency has increased with

the increase of MAH and DCP content. The selection for the best strategy of EPDM-g-MAH

grafting then implemented using the optimization menu available in the DOE software. The

upper limit and the lower limit are considered to be within the range of 2.50 – 7.50 wt.% and

0.10 – 0.50 wt.% for MAH and DCP content, respectively. The grafting efficiency has been

set to a maximum increase up to 8.52%. Re-experiment has found that the experimental

DESIGN-EXPERT PlotAbsorbance Ratio

A: MAH ContentB: DCP Content

Half Normal plot

Half N

orm

al %

pro

babi

lity

|Ef f ect|

0.00 1.12 2.24 3.36 4.48

0

20

40

60

70

80

85

90

95

97

99

A

B

AB


5434

reproducibility generates only 9.30% of deviation value over the proposed output by the

optimization tool.

Next, the success of EPDM-g-MAH grafting process then confirmed analytically by

using a nuclear magnetic resonance (NMR) spectroscopy. Observation using NMR spectral

helps in the proposed reaction mechanism of MAH grafting into EPDM rubber with DCP as

initiator. Figure 7 and Figure 8 present the 1H-NMR results for EPDM control sample and

EPDM-g-MAH from optimum EM2 sample. Meanwhile, two-dimensional analysis results

using 2D-COSY NMR spectra for both samples are shown in the following Figure 9 and

Figure 10.

Referring to Figure 7, the presence of resonant signal at 0.8356 ppm showed the

presence of CH3 from the propyl group found on the EPDM backbone, while the resonant

signal around 1.10 ppm showed the CH2 on the EPDM and the signal around 2.0574 ppm

was CH and CH2 groups adjacent to olefin. The resonant signal at 4.9956 ppm was the

vynilidene termination for EPDM, and the peak at 5.2310 ppm was the internal olefin of the

diene on the terpolymer part. The EPDM aromatic part is shown as a weak resonant signal

peat at 7.0 ppm. Grafting of MAH on the EPDM backbone has shifted some of the resonant

signals found in the control sample with the presence of new peak detected at signal 4.00

ppm (Figure 8). The presence of new singlet from the peak of 4.00 ppm is the effect of ene

reactions [17]. The absence of resonant at peak 6.50 ppm in the 1H-NMR spectra for the

EPDM-g-MAH sample and its control sample, explains that terpolymer MAH has been

detected from this analysis [31-34].

Figure 6. Response surface plot for MAH grafting efficiency using the quantity ratio

approach.

DESIGN-EXPERT Plot

Absorbance RatioX = A: MAH ContentY = B: DCP Content

1.54

3.285

5.03

6.775

8.52

Abs

orba

nce

Rat

io

2.50 3.75

5.00 6.25

7.50

0.10

0.20

0.30

0.40

0.50

A: MAH Content B: DCP Content


5435

Figure 7. 1H-NMR for pure EPDM rubber (control sample).

Figure 8. 1H-NMR for grafted EPDM-g-MAH (EM2) sample.


5436

Figure 9. 2D-COSY for pure EPDM rubber (control sample).

Figure 10. 2D-COSY for grafted EPDM-g-MAH (EM2) sample.

The grafting MAH reaction mechanism into EPDM visualized as in the following Figure 11.

This reaction mechanism has supported by the 1H-NMR and 2D-COSY NMR analysis as

presented in the Figure 7 - 10. Those figures are original results that taken directly from the

NMR machine and presence of noise and its background colour need to be ignore due to

machine set-up, standard results and machine condition. The EPDM-g-MAH compatibilizer

synthesized by using an internal mixer, which gives shearing effect that can help in breaking

the chain [32, 33]. The presence of dicumyl peroxide initiator in very small quantities as

shown in reaction schematic (1), has formed the start-up radical for reactive grafting reaction


5437

of EPDM rubber. DCP radicals react with hydrogen atoms from the EPDM backbone to

produce EPDM radicals as shown in the reaction scheme (2).

Figure 11. Proposed reaction mechanism model for EPDM grafting with MAH

(EPDM-g-MAH).

The presence of DCP initiator in certain small quantity has helped in increasing the number

of EPDM active radicals for the reaction with MAH. In the reaction schematic path (3), the

MAH molecules added during the melt-blending were found to react with EPDM active

radicals and grafting occurred in the formation of EPDM-g-MAH radicals, followed by

several possibilities for termination reactions, based on two paths of reaction options [32, 33,

34]. Option (1) shows the EPDM-g-MAH radicals may undergo hydrogen transfer from other

DCP Radical

EPDM Rubber

MAH EPDM-g-MAH

EPDM-g-MAH (I)

Hydrogen transfer from

EPDM other chains

EPDM-g-MAH (II)

EPDM radical has been reacted with other radical

(MAH, EPDM or other primer radicals)

OPTION 1 OPTION 2


5438

polymer chains, whereas option (2) shows the possible radical reaction of EPDM-g-MAH

with other radicals in the melt blending system such as MAH, EPDM or primary radicals to

form different EPDM-g-MAH structures [9].

CONCLUSIONS

As a conclusion, preparation of EPDM-g-MAH compatibilizer in the laboratory scale using

an internal mixer has successfully performed in this study, by applying a two level full

factorial experimental design method with higher R2 value of 99.97%. Interestingly, the

MAH grafting efficiency was determined by applying the standard calibration curve and

Beers Lambert absorbance law. 3D response surface curve has established the relationships

between MAH and DCP content as independent variables towards the grafting efficiency

response. Optimum grafting efficiency output up to 8.52% was obtained form 7.5 phr MAH

and 0.50 phr DCP with about 67.45% of effects list has contributed solely by the DCP content

factor. At the end, from the FTIR, 1H-NMR and 2D-COSY spectral analysis has suggested

that there are three (3) schematic reaction mechanism route with two (2) possible termination

option for synthesizing the EPDM-g-MAH compatibilizer. This study provides the

sustainability value on the possibility of EPDM-g-MAH compatibilizer development at the

laboratory scale with higher yield and low cost requirements.

ACKNOWLEDGEMENTS

The authors would like to thank to the Universiti Teknikal Malaysia Melaka and Universiti

Malaysia Pahang for laboratory facilities and financial assistance under UTeM Hi-Impact

Short Term Research Grant (PJP/2016/FKP/H16/S01484) and UMP Fellowship Research

Grant project No. RDU1703321.

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on the preparation of epdm-g-mah compatibilizer via melt

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